Treatment of artificial materials



Patented Aug. 17, 1943 Henry Dreyfus, London, England, assignor toCelanese Corporation of America, a corporation of Delaware No Drawing.Application March 6, 1942, Serial 11 Claims.

This invention relates to improvements in the treatment of artificialfilaments and other products and is more particularly concerned withimproving the tenacity and/or the extensibility of such materials.

This application is a continuation-in-part of my application S. No.318,711, filed February 13, 1940.

It has been known for some time that the tenacity of materials made oforganic derivatives of cellulose is increased by stretching the mate-vrials, the stretching being facilitated by so-called assisting agentswhich are solvents or strong swelling agents for the organic derivativeof cellulose. A large number of such assisting agents has been proposedincluding both water-miscible and water-immiscible agents. In generalthe stretching is best carried out on the running filaments or otherproducts which, after being gripped by a pair of nip rollers or othernon-slip feed device, may he carried through a bath of l the assistingagent and be taken up at the other end of the bath by a similar pair ofrollers or other feed device rotating at a higher speed than the feed-indevice. It is generally advantageous to arrange that the stretch takesplace in stages In Great Britain February 22,

' these materials are considerably improved by apby arranging a numberof gripping devices along the bath, the various devices rotating atincreasing speeds as the filament proceed along the bath. However, thesecond set of grippingdevices may rotate at the same speed as the feedinset, so as not to impart a stretch during the preliminary soaking of thematerial.

As is well known, it is of great importance in textile-formingoperations, e. g. weaving and knitting, that the yarns or otherfilamentary materials should possess a considerable extensibility sothat they may be able to withstand the relatively violent tensioning andflexing to. which they are subjected during those operations. In U. S.Patent No. 2,058,422, processes are described whereby the extensibilityof materials made of organic derivatives of cellulose is increased bymay, for example, be produced by stretching already formed, for exampledry-spun, cellulose derivative filaments ortyarns by the processesdescribed above, e. g. by those of U. S. Patent No. 2,047,195 andBritish Patents Nos. 323,790, 370,430 and 378,074 using organic solventsas the stretch-assisting agents, or by the processes of U. S. PatentsNos. 2,142,717 and 2,142,722 and British Patents Nos. 438,584, 538,585,438,586, and 438,587 using steam or hot water under pressure as thestretch-assisting agent. Again, in the wet .spinning processes of U. S.Patents Nos. 2,147,640,

plying the treatment of U. S. Patent No. 2,058,422 to increase theirextensibility.

The present invention relates to a new method of applyingwater-insoluble organic solvents, latent solvents and other swellingagents which are to serve as stretch-assisting agents in op-' erationswhereby the tenacity of the treated materials may be increased or asshrinking agents in treatments whereby the treated materials may .begiven an improved power of withstanding textile-forming operations.According to the pres ent invention these agents are applied to thematerials, such as, for example, yarns and filaments,

before they'are subjected to a textile-forming operation, in the form ofaqueous emulsions. By this means, the tendency of the constituents ofthe bath, particularly highly volatile constitu- .ents, to evaporate isconsiderably reduced, and

' in consequence it is much easier to maintain the subjecting thematerials, in the absence of tension suificient to stretch them, totreatment with organic solvents, latent solvents or swelling agents. Thetreatment is of greatest value for improving the extensibility offilaments, yarns and the like of cellulose derivatives which have eitherduring or subsequent to the spinning operation been subjected to astretch for the purpose of improving the tenacity. Such an increased tenacity, for example a tenacity of 3 or 4 grams per denier or more, isusually accompanied by an undesirably low extensibility. Such materialscomposition of the bath constant. Moreover, when employing the aqueousemulsions according to the invention there is no need to dry thematerials out before they are treated with the emulsions and further thepossible shrinkage which the materials undergo may be readilycontrolled.

The emulsions may be made up in any desired manner and are usually bestprepared with the aid of emulsifying agents, for example soaps, e. g.alkali metal and ammonium soaps, and ethanolamine and other organicsoaps, particularly soaps of saturated higher fatty acids, sulphonatedfatty alcohols, the alkylated naphthalene sulphonic acids, andparticularly the higher alkylated naphthalene sulphonic acids, such ascetyl naphthalene sulphonic acid, and the Twitchl ype of fatspllttingagent obtained, for ex ample, by the sulphonation of a mixture ofnaphthalene and castor oil. If desired, the emulsions may be stabilisedwith the aid of suitable protective colloids, e. g. a water-solublemethyl cellulose.

The most important class of swelling agents for use according to thepresent invention comprises the latent solvents, particularly thechlorinated hydrocarbons, e. g. methylene chloride, ethylene chlorideand chloroform. The disperse phase in the emulsion may consist of 100%of the latent solvent or other water-insoluble swelling agent for thecellulose derivative, or the swelling agent may be suitably diluted inthe disperse phase with water-insoluble diluents, for

perchlorethylene and other chlorinated or halogenated compounds whichare inert or comparatively inert towards the cellulose derivatives.

Preferably the swelling agent constitutes at least about 50% by volumeof the disperse phase. For example, a very suitable disperse phase forthe treatment of ordinary acetone-soluble cellulose acetate materialsconsists of a solution of methylene chloride in benzene, high-boilingpetroleum or carbon tetrachloride having a concentration of the order of5080% by volume. The concentration of the' disperse phase in theemulsion may be set at any desired value. The lower concentrations ofthe disperse phase'are more suitable where hanks are being treated andwhere the time of treatment is comparatively long. However, with a viewto uniformity of treatment it is undesirable to employ concentrations ofthe disperse phase of much under 10% by volume, and for the treatment oftravelling materials it is preferable that the concentration should beconsiderably higher, for example over 20%, especially 30-50 or 55% byvolume.

The temperature of treatment depends upon the degree of modification ofcharacteristics which is desired, upon the nature of the materialstreated, and :upon the nature and concentrations of the treatmentmedium. In general, however, a temperature of the order of l5-30 C., e.g. 25 C., is preferable. The treatment may be carried out undersuper-atmospheric pressure, if desired, with a view to accelerating theaction of the medium, though, in general it is preferable to 'treathanks of ma terial under normal pressure, in which case a time oftreatment of minutes is usually found suflicient to producesubstantially the maximum increase in extensibility for the particularmedium or to give substantially the maximum degree of stretchassistance. The time of treatment may, however, be extended up to one ortwo hours or more, if desired. When treating the treatment liquor bymeans of rollers suit-- ably disposed in the liquor or above the liquor,in the latter case suitable guides being provided to immerse thefilaments or yarns. Alternatively,

the materials in hank form or travelling materials may be sprayed withthe emulsions. A treatment of travelling materials is particularlyconvenient when it is desired to stretch the materials. A veryconvenient arrangement for the treatment of travelling materials is tocarry the materials successively round a number of sets of rollers, eachset consisting of three-rollers arranged at the apices of a triangle.The base of the triangle may be uppermost and the two rollers formingthe base may be above the liquor, the remaining roller being in theliquor, or if desired this arrangement may be inverted, or alternativelythe whole of the set of rollers may be out of the liquor and may beirrigated or sprayed with the emulsion of the solvent or swelling agent.Again, the materials may pass in contact with the upper surface of oneor more rollers which dip into a'bath of emulsion so as to carry a filmof liquor from which the materials take up an appropriate amount. Evenwhere some of the rollers of each set dip into the liquor it isdesirable to irrigate or spray the rollers which are out of the liquor.The rollers-may be arranged so that each set runs at a regulated higheror lowerspeed than the preceding set so as to stretch the materials orto enable shrinkage totake place. As already indicated, in some .caseswhen it is desired to stretch the materials,

particularly with assisting agents havinga comparatively low penetrativepower, it-is desirable that the second set of rollers should run at thesame speed or even a slightly reduced speed as compared with the firstset, so as to enable the materials to be thoroughly soaked.

In order to avoid the delustering action of hot aqueous media oncellulose derivative materials in the presence of organic swellingagents, washing of the materials with aqueous media should be carriedout at temperatures which do not exceed about 60 C., and preferably attemperatures of the order of 15-30" C. Removal of the organic swellingagents should accordingly precede any treatments with hot aqueous mediato which it may be desired to subject the materials. The materials arepreferably freed from the organic swelling agent by washing with anaqueous solution of an emulsifying agent, especially an aqueous solutionof any emulsifying agent present in the treatment medium, followed by awater wash. However, other methods of removing the medium may beemployed, e. g. a simple washing with water, particularly whereuniformity of appearance in .the products is of subsidiary importance.

The present. invention enables the materials to be stretched within verywide limits; for instance comparatively 'small-stretches may beimparted, e. g. of the order of 20-100% of the original length of thematerials, or very much larger stretches such as 500-1000% or evenseveral thousand per cent of the original length.

The stretched materials have an increased tenacity as compared with thestarting materials. In some cases it is, however, desirable to subjectthem to a further process with the object of improving thcirextensibility. With this object in view they may be treated with agentswhich have a tendency to shrink the materials. Shrinking is notabsolutely necessary, though it is desirable, and in this connectiongeneral reference is made to U. 5. Patent No. 2,058,422 which has thisgeneral object. As indicated in that specification, shrinkage of theorder of 51-15% on the stretched length of the materials gives a verysatisfactory increase in the extensibility of the stretched materials.Again, as indicated in that specification, the shrinking may take placecontinuously with the stretching operation, and indeed with the sameagents as those used for stretching. Such agents may again be used inemulsified form as described above. In such a case the materials may bestretched by means of sets of rollers as described above, and thencarried on to further sets of rollers driven at such speeds as topromote shrinkage of the materials,

' all the rollers being irrigated and/or sprayed with the emulsion ofthe agent used both to facilitate stretching and to bringaboutshrinkage.

It is to be understood that improvement in the materials can be effectedeven where the filaments or yarns are neither stretched nor shrunk, i.e. where they are held against shrinkage under a tension insufficient tostretch them. I However, the best increase in extensibility is obtainedwhen actual shrinkage takes place, for example a shrinkage of the orderof 55-15% on the initial length of the materials under treatment, thisbeing particularly the case with materials which have been stretched andwhich have a tenacity exceeding 2 grams per denier.

Acetone-soluble cellulose acetate has been mentioned in the precedingdescription, and this is the most important cellulose derivative.However, the invention is also applicable to the treatment of filaments,yarns and the like of other.

cellulose derivatives, for example cellulose formate, propionate,butyrate, nitro-acetate, acetate-propionate and acetate-butyrate andethyl and benzyl celluloses as well as cellulose ether- .esters andmixed ethers. Further, in addition to the treatment of filaments, yarnsand the like,

the invention is also of importance for improvume) with the aid of 1% byweight of ammo-- nium stearate. After minutes the yarn is withdrawn fromthe medium, washed at 25 C. first with a 1% solution of ammoniumstearate in water and then with water, and finally dried in a stream ofair. It is found to be well shrunk and to show a high extensibility.

Example 2 Dry-spun cellulose acetate yarn is withdrawn from bobbins andled to a series of rollers adapted to stretch it in eight stages by 250%of its original length. Before reaching-r the first of such rollers theyarn is passed through a bath of an emulsion comprising a mixture of 75parts of methylene chloride and 25 parts of high boiling petroleumdispersed in 100 parts of water (all parts by volume) with the aid of 1%ammonuim palmitate and the same medium is sprayed on to the travellingyarn between each stage of stretching. The yarn is then passed overthree rollers irrigated with a 1% ammonium palmitate solution in waterand through a bath of water, and is finally dried in a stream of air.All the liquid media are maintained at 25 C.

Example 3 The yarn produced according to Example 2 is treated by theprocess of Example .1 and then found to possess a good tenacity andextensibility.

Having described my invention, what I desire to secure by Letters Patentis:

1. Process for increasing the extensibility of artificial filaments,threads, yarns and like materials containing organic derivatives ofcellulose, which comprises subjecting stretched materials, before theyare subjected to a fabric forming operation, to the action of an aqueousemulsion having in disperse phase a -i'trater-insoluble-or-- ganicswelling agent and substantially removing said agent from the materialsbefore they are subjected to the action of any hot aqueous medium. 4

2. Process for increasing the tenacity and the extensibiliy of.artificial filaments, threads, yarns and like materials containingorganic derivatives of cellulose, which comprises stretching thematerials While they are under the action of an aqueous emulsion havingin disperse phase a water-insoluble organic swelling agent, permittingsaid materials, before they are subjected to a fabric-forming operation,to shrink while under the action of an aqueous emulsion having indisperse phase a water-insoluble organic swelling agent andsubstantially removing said agent from the materials before they aresubjected to the before they are subjected to a fabric-forming operationand in the absence of tensionsufiicient to stretch them, to treatmentwith an aqueous emulsion having in disperse phase a water-insolubleorganic swelling agent and substantially removing said agent from thematerials before they are subjected to the action of any hot aqueousmedium.

4. Process for increasing the extensibility of artificial filaments,threads, yarns and like'materials containing cellulose acetate, whichhave been stretched to increase their tenacity, which comprisessubjecting the materials, before they are subjected to a fabric-formingoperation-and in the absence of tension suflicient to stretch them, totreatment with an aqueous emulsion having in disperse phase awater-insoluble organic swelling agent and substantially removing saidagent from the materials before they are subjected to the action of anyhot aqueous medium.

5. Process for increasing the extensibility of artificial filaments,threads, yarns and like materials containing organic derivatives ofcellulose,

which have been stretched to increase their tenacity, which comprisessubjecting the materials before they are subjected to a fabric-formingoperation and in the absence of tension sufiicient to stretch them, totreatment with an aqueous are subjected to the action of any hot aqueousmedium.

6. Process for increasing the extensibility of artificial filaments,threads, yarns and like materials containing organic derivatives ofcellulose, which have been stretched to increase their tenacity, whichcomprises subjecting the materials before they are subjected to afabric-forming operation and in the absence of tension sufficienttostretch them, to treatment with an aqueous emulsion of which thedisperse phase comprises at least about 50% of a water-insoluble fromthe materials before they are subjected to organic swelling agent andsubstantially removing said agent from the materials before they aresubjected to the action of any hot aqueous medium.

. '7. Process forincreasing the extensibility of artificial filaments,threads, yarns and like materials containing organic derivatives ofcellulose, which have been stretched to increase their tenacity,which'comprises subjecting the materials, before they are subjected to afabric-forming operation and in the absence of tension sufiicient tostretch them, to treatment with an aqueous emulsion of which thedisperse phase comprises at least about 50% of a water-insoluble organicswelling agent and constitutes at least about 1 of the emulsion andsubstantially removing said agent from the materials before they aresubjected to the action of any hot aqueous medium.

, 8. Process for increasing the extensibility of artificial filaments,threads, yarns and like materials containing organic derivatives ofcellulose, which have been stretched to increase their tenacity, whichcomprises subjecting the materials, before" they are subjected to afabric-forming operation and in the absence of tension sufiicient tostretch them, to treatment with an aqueous emulsion of which thedisperse phase comprises at least about 50% of a water-insoluble organicswelling agent and constitutes 30-50% of the emulsion and substantiallyremoving said agent subjected to any hot aqueous medium.

10. Process for increasing the extensibilityof artificial filaments,threads, yarns and like materials containing organic derivatives ofcellulose, which have been stretched to increase their tenacity, whichcomprises subjecting the materials before they are subjected to afabric-forming operation and in theabsenceof tension sufficient tostretch them, to treatment with an aqueous emulsion having in dis ersephase a waterinsoluble organic swelling agent, said emulsion beingprepared with the aid of an emulsifying agent, and substantiallyremoving said agent from the materials before they are subjected to theaction of any hot aqueous medium.

11. Process for increasing the extensibility of artificial filaments,threads, yarns and like materials containing organic derivatives ofcellulose, which comprises subjecting stretched materials, before theyare subjected to 'a fabricformin'g operation, to the action of anaqueous emulsion having in disperse phase a water-insoluble organicswelling agent, said emulsion being stabilized with the aid of aprotective colloid, and substantially removing said agent from thematerials before they are subjected to the action of any hot'aqueousmedium.

HENRY DREYFUS.

